Holder for tip and method for manufacturing the same, and scribing device and manual cutter that are provided with the holder for tip

ABSTRACT

A chip holder has a cutter chip having a conical shaft at both sides thereof. Concaves for supporting the cutter chip are bell-shaped having a curve with a predetermined radius of curvature. In an example, solid lubricant may be supplied from the outside of the holder to the concave of the chip holder. Thus the life of the cutter chip can be extended.

TECHNICAL FIELD

This invention relates to a chip holder with a cutter chip, itsfabrication method, a scribing apparatus and a manual cutter therewith.

BACKGROUND ART

A chip holder, having a cutter chip at the lower end thereof, isemployed to scribe a line on a surface of a plate made of a brittlematerial for separating the plate into pieces. FIG. 1 shows examples ofprior art cutter chips 2 disclosed in Japanese Utility Model Publication62-023779/1987. As shown in (a) in FIG. 1, the cutter chip 2 has a shapehaving two cones sharing a common base, and two peaks thereof are usedas a shaft of the cutter chip 2. Further, as shown in (b), (c) and (d)in FIG. 1, the cutter chips 2 may have concave gradients, convexgradients and R-chamfered peaks. The cutter chip 2 may be made ofsintered diamond. In the chip holder, friction of the chip againstbearings used to support the chip becomes low, and the life for scribingof the chip is extended.

Recently, for liquid crystal panels and the like fabricated by using ascribing process, it is highly demanded to decrease the price of an endproduct, and it is requested to decrease the cost for scribing and toincrease the efficiency of scribing further. As to a chip holder, it isneeded to increase the life of chip holder for scribing.

DISCLOSURE OF INVENTION

An object of the invention is to provide a chip holder having a higherscribing efficiency and a longer scribing life.

A chip holder according to the invention includes a cutter chip having aconical shaft at both sides of a circular ridge line of a cutting edgethereof, two holders; and two bearings for holding the cutter chip,provided at opposing sides of the two holders. Each of the two bearingshas a bell-shaped concave for supporting the cutter chip.

Preferably, the bell-shaped concave has a curved plane having apredetermined radius of curvature.

Preferably, the bell-shaped concave is not through to the holder.

Preferably, the bell-shaped concave is not through to the holder, andthe radius of curvature is 0.1D to D wherein diameter of cutting edge ofthe cutter chip is represented as D.

Preferably, the bell-shaped concave is extended to the holder.

Preferably, the bell-shaped concave is extended to the holder, and theradius of curvature is D to 2D wherein diameter of cutting edge of thecutter chip is represented as D.

Preferably, the bearings are made of monocrystalline diamond.

Preferably, the bearings are made of sintered diamond.

In a method according to the invention for producing a chip holderhaving a cutter chip having a conical shaft at both sides of a circularridge line of a cutting edge thereof, a bell-shaped concave is formed ata bearing for supporting the cutter chip, a bearing holder holding thebearing are mounted into each of first and second holder members, and acutter chip is combined with the first and second holder members havingthe bearings.

Preferably, the bearing is made of monocrystalline diamond.

Preferably, the concave with the bell shape is fabricated with a YAGlaser.

Preferably, the bearing is made of sintered diamond.

Preferably, the bell-shaped concave is formed with electric dischargingmachining.

A scriber apparatus according to the invention includes a mechanism formoving a scribing head in X and/or Y direction relatively to a table onwhich a plate made of a brittle material is put. The scribing headprovides one of the chip holders mentioned above.

A manual cutter according to the invention has a cylindrical grip, and achip holder fixed to an end of the grip. The chip holder is one of thechip holders mentioned above.

An advantage of the invention is that the life of the cutter chip andthe chip holder can be extended because the precision of rotation of thecutter chip is improved and the friction resistance at the bearings canbe decreased by supplying solid lubricant according to the structure ofthe chip holder having chip holders with recesses to support a cutterchip of a shape of two cones sharing a common base, each of the recesseshaving a concave with a predetermined radius of curvature.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of prior art cutter chips to be held by a holder;

FIG. 2 is an enlarged, schematic view of a chip holder in a regionaround a chip and a bearing therefor;

FIG. 3 is a diagram of a prior art wire-drawer around a dice thereof;

FIG. 4 is a diagram for a front view and a side view of a chip holder;

FIG. 5 is an enlarged, schematic view of a chip holder in a regionaround a chip and a bearing therefor according to a first embodiment;

FIG. 6 is an enlarged, schematic view of an example of a chip holder ina region around a chip and a bearing therefor according to a secondembodiment;

FIG. 7 is an enlarged, schematic view of an example of a chip holder ina region around a chip and a bearing therefor according to a thirdembodiment;

FIG. 8 is a diagram on fabrication steps of a bearing for the chipholder according to the third embodiment;

FIG. 9 is a front view of a scribing apparatus with the chip holderaccording to the invention;

FIG. 10 is a side view of the scribing apparatus shown in FIG. 9; and

FIG. 11 is a partial sectional view of a manual cutter with a chipholder according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,embodiments of the invention are explained below.

The inventors studied prior art chip holders in order to improvefabrication efficiency and for extending the life thereof for scribing.FIG. 2 shows an example of a prior art cutter chip 2 and bearings 3 a ofa holder 1 for the chip 2 in detail. The bearings 3 a support the cutterchip 2 at two sides thereof. They are made of sintered diamond. Asupporting section 3 b to be in contact with the cutter chip 2 has aconical concave to abut along the contour of the cutter chip 2. Based ona test on the life of the cutting edge of the cutter chip 2, in order toextend the life of the cutting edge of a cutter chip 2, it is found moreeffective to decrease friction resistance between the cutter chip 2 andthe supporting section 3 b to improve the precision on the rotation ofthe cutter chip 2, rather than to prevent wear and tear of the cuttingedge of the cutter chip 2. That is, it is desirable to improve theprecision on the rotation of the cutter chip 2 to decrease the wear ofthe shaft of the cutter chip 2 and of the bearings 3 a.

FIG. 3 shows a die of a withdrawing machine for drawing a wire S inorder to decrease its diameter. The die has regions called as bell(entrance), approach, reduction, bearing, back relief and exit. It ismade of diamond by taking the life thereof and the precision of drawinginto account. The inner area of the die for drawing has a shapeappropriate for the precision of the drawing, wear resistance and highstrength, and its section has a gradual curve.

The inventors find that when the supporting section 3 b of a chip holderhas a bell shape curve as shown in FIG. 3 instead of the conical shapecurve shown in FIG. 2, the resulting stable linear contact of the cutterchip 2 at the supporting section 3 b improves centrality and rotationprecision of the cutter chip. Thus, the life for scribing of the cuttingedge becomes longer.

FIG. 4 shows a front view and a side view of a chip holder 1 for cuttinga brittle material. At the lower portion of the chip holder, two holdermembers 1 a and 1 b are provided in parallel, and they support a chip 2between them roratably with bearings not shown. The chip holder 1 has anintegral body including the holder members 1 a and 1 b, and a cutterchip 2 is fitted to the lower portion of the integral body to constructa chip holder 1. After binding the holder members 1 a and 1 b with apredetermined gap between them to hold the cutter chip 2 rotatably, thechip holder 1 can be used for a desired use.

FIG. 5 shows a section of a chip holder 20 of a lower portion thereof.Bearing supporters 6 are fixed, for example, with soldering intocircular recess provided in planes of the first holder member 20 a andthe second one 20 b facing to each other. The bearing supporters 6 aremade of, for example, Fe—Cu—Sn sintered metal, and it has been sinteredwith a bearing 5 a made of monocrystalline diamond to have a cylindricalshape. The cutter chip 2 has a conical shaft at two sides of a circularridge line of a cutting edge thereof. The supporting section 5 b on thesurface of the bearing 5 a has a bell-like shape similar to the bellregion shown in FIG. 3. For example, if the diameter of the circularridge line of the cutting edge of the cutter chip 2 is 2 mm, the radiusof curvature of the above-mentioned curve is about 0.2 to 2 mm. Further,if the radius of the cutting edge of the chip 2 is denoted as D inmillimeter, the radius of curvature of the curve is selected in a rangebetween 0.1D and D in millimeter.

The supporting section 5 b forms a non-through recess, as shown in FIG.5. That is, the recess of the supporting section 5 b is not through tothe bearing 5 a. In this case, solid lubricant is supplied from the sideof the cutter chip 2. The solid lubricant is, for example, tungstendisulfide or molybdenum disulfide having characteristics, for example,that it can be used in a wide temperature range and that it is hard tobe vaporized.

FIG. 6 shows a chip holder 20 in a lower portion according to a secondembodiment of the invention. Similarly to the lower portion of the chipholder of the first embodiment, bearing supporters 6 and bearings 7 aare fixed into circular recess provided in planes of a first holdermember 20 a and a second one 20 b facing to each other. The supportingsection 7 b has a throughhole 7 d, and it is closed by the bearingsupporter 6.

FIG. 7 shows a chip holder 20 in a lower portion according to a thirdembodiment of the invention. Similarly to the lower portion of the chipholder of the second embodiment, bearing supporters 6 and bearings 7 aare fixed into circular recess provided in planes of a first holdermember 20 a and a second one 20 b facing to each other. The supportingsection 7 b has a throughhole 7 d, while a throughhole 7 c is alsoformed through the bearing supporter 6 and the holder member 20 a, 20 bso as to align with the throughhole 7 d. The throughholes 7 c and 7 dare used as an inlet to supply solid lubricant from the outside of theholder 20.

Further, in this case, the supporting section 7 b has the circular ridgeline of cutting edge with the radius of curvature of, for example, about3 to 6 mm when the diameter of the cutting edge of the cutter chip 2 is3 mm. Further, if the diameter of the cutting edge of the cutter chip 2is denoted as D mm, the radius of curvature of the curve is selected ina range between D and 2D mm.

The chip holders according to the invention correspond to a structurewherein the two holder members 1 a and 1 b shown in FIG. 4 are replacedwith the first and second holder members 20 a and 20 b according to oneof the above-mentioned first to third embodiments.

FIG. 8 illustrates an embodiment of a fabrication process for a bearing7 a made of monocrystalline or sintered diamond. When the bearing 7 a ismade of monocrystalline diamond X, top and bottom parts of the diamondX, shown in (a) in FIG. 8A with hatching, is cut off with a skeif or thelike, and a bell-shaped hole is formed at its center with a yttriumaluminum garnet (YAG) laser as a basis of the supporting section 7 b((b) in FIG. 8). Then the hole is rounded with a YAG laser to have apredetermined outer contour for the bearing 7 a ((c) in FIG. 8). Thenlapping is performed as shown in (f) in FIG. 8. In this step, while freegrains (diamond grains of 2 to 4 μm) are supplied to the bearingsupporter 7 b, a needle 12 having the same tip angle as the bearingsupporter 7 b is rotated and swung further around the hole so as not todeform the bell shape.

When a bearing 7 a made of sintered diamond is fabricated, diamondgrains are first sintered to provide a cylindrical bearing 7 a′ having apredetermined outer diameter ((d) in FIG. 8). Next, the cylindricalbearing 7 a′ is subjected to electric discharge machining by using adischarge electrode 11 having a contour similar to the bell shape, andthe bell shape is transferred to the cylindrical bearing 7 a′ ((e) inFIG. 8). Then, while grains (diamond grains of 2 to 4 μm) are suppliedto the surface subjected to the electric discharge machining, a needle12 having the same tip angle as the bearing supporter 7 b is rotated andinclined around the hole so as not to break the bell shape ((f) in FIG.8).

The bearing 7 a may be made of a gem such as sapphire or ruby. Thelapping is not limited to the above-mentioned process, and for example,wire lapping may be used.

In order to fabricate a chip holder according to the invention, bearings5 a, 7 a having the above-mentioned bell-shaped recess are held by thebearing holders 6 and mounted to the first and second holder members 20a and 20 b. Next the cutter chip 2 is combined with the first and secondholder members 20 a and 20 b having the bearings 5 a, 7 a.

Scribing tests are performed on the chip holders with edge load of 1.0kg, and the running distance (or life) thereof is determined as a resultof the endurance test. As to prior art chip holders shown in FIG. 2, therunning distance is 150,000 meters on the average, while it is extendedlargely to 300,000 meters on the average for the chip holders of theinvention. Further, by supplying solid lubricant every 10,000 meters,the life of the cutting edge is extended further by about 20 to 30%.

By using the bearing 5 a, 7 a impregnated with oil at the bearingsupporter 5 b, 7 b, or so-called oiless bearing, for supporting thecutter chip 2, periodic refill for solid lubricant is not needed, andstable scribing performance can be kept. Alternatively, the bearingsupporter 5 b, 7 b may be coated for improving the surface property andfor hardening the surface (for example, defric coating) in order toextend the life of the bearings 5 a, 7 a.

Next, a scribing apparatus is explained having the above-mentioned chipholder. FIGS. 9 and 10 are a front view and a side view of the scribingapparatus. A plate 50 made of a brittle material put on a horizontalrotatable table 51 is fixed on the table 51 by absorbing the plate witha vacuum pump (not shown), and a pair of parallel guide rails 52 supportthe table 51 and can guide it in Y direction (perpendicularly to thesheet of paper in FIG. 9) along the rails 52 with a ball screw 53. Aguide bar 54 is provided above the table 51 in X direction(left-and-right direction in FIG. 9). A scribing head 55 is mounted onthe guide bar 54 so as to slide in X direction, and a motor 56 isprovided to slide the scribing head 55. The above-mentioned chip holder20 is attached below the scribing head 55 so as to rise and fall and toswing around an axis perpendicular to the plat 50, and the cutter chip 2is mounted rotatably at the lower end thereof. A pair ofcharge-coupled-device (CCD) cameras 58 are arranged above the guide bar54 to recognize alignment marks provided on the plate 50 put on thetable 51. Further, a cutter chip inverter is included in the scribinghead 55 for inverting the direction of the chip holder 20 by 180 degreesso as to invert the cutter chip by 180 degrees each time a scribing lineis formed.

FIG. 11 shows a manual cutter having the above-mentioned chip holder. Acylindrical holder 61 for holding the manual cutter is the same asdisclosed in Japanese Utility Model Publication 62-23780/1987 by theapplicant, and the above-mentioned chip holder 20 is mounted on itsbottom. The manual cutter can be used not only for a glass plate, butalso for a plate made of a brittle material such as a ceramic or asemiconductor material. Further, the manual cutter includes an oilchamber 63, a cap 64 thereof and mechanisms 65-73 therefor, but they arenot directly related to the invention, and explanation thereof isomitted here.

Although the present invention has been fully described in connectionwith the embodiments thereof with reference to the accompanyingdrawings, it is to be noted that the invention is not limited to theseembodiments.

1. A chip holder comprising: a cutter chip having a conical shaft atboth sides of a circular ridge line of a cutting edge thereof; twoholders; and two bearings for holding said cutter chip, provided atopposing sides of said two holders; wherein each of said two bearingshas a bell-shaped concave for supporting said cutter chip.
 2. The chipholder according to claim 1, wherein said bell-shaped concave has acurved plane having a predetermined radius of curvature.
 3. The chipholder according to claim 1, wherein said bell-shaped concave is notthrough to said holder.
 4. The chip holder according to claim 2, whereinsaid bell-shaped concave is not through to said holder, and the radiusof curvature is 0.1D to D wherein diameter of cutting edge of saidcutter chip is represented as D.
 5. The chip holder according to claim1, wherein said bell-shaped concave is extended to said holder.
 6. Thechip holder according to claim 2, wherein said bell-shaped concave isextended to said holder, and the radius of curvature is D to 2D whereindiameter of cutting edge of said cutter chip is represented as D.
 7. Thechip holder according to claim 1, wherein said bearings are made ofmonocrystalline diamond.
 8. The chip holder according to claim 1,wherein said bearings are made of sintered diamond.
 9. A method forproducing a chip holder having a cutter chip having a conical shaft atboth sides of a circular ridge line of a cutting edge thereof,comprising the steps of: forming a bell-shaped concave for a bearing forsupporting the cutter chip; mounting a bearing holder holding thebearing into each of first and second holder members; and combining acutter chip with the first and second holder members having thebearings.
 10. The method according to claim 9, wherein said bearing ismade of monocrystalline diamond.
 11. The method according to claim 10,wherein said concave with the bell shape is fabricated with a YAG laser.12. The method according to claim 9, wherein said bearing is made ofsintered diamond.
 13. The method according to claim 12, wherein thebell-shaped recess is formed with electric discharging machining.
 14. Ascriber apparatus comprising a mechanism for moving a scribing head in Xand/or Y direction relatively to a table on which a plate made of abrittle material is put, wherein said scribing head comprises a chipholder according to claim
 1. 15. A manual cutter comprising: acylindrical grip; and a chip holder fixed to an end of said grip,wherein said chip holder is one of the chip holders according toclaim
 1. 16. The chip holder according to claim 2, wherein saidbell-shaped concave is not through to said holder.
 17. The chip holderaccording to claim 2, wherein said bell-shaped concave is extended tosaid holder.
 18. The chip holder according to claim 2, wherein saidbearings are made of monocrystalline diamond.
 19. The chip holderaccording to claim 3, wherein said bearings are made of monocrystallinediamond.
 20. The chip holder according to claim 4, wherein said bearingsare made of monocrystalline diamond.
 21. The chip holder according toclaim 5, wherein said bearings are made of monocrystalline diamond. 22.The chip holder according to claim 6, wherein said bearings are made ofmonocrystalline diamond.
 23. The chip holder according to claim 2,wherein said bearings are made of sintered diamond.
 24. The chip holderaccording to claim 3, wherein said bearings are made of sintereddiamond.
 25. The chip holder according to claim 4, wherein said bearingsare made of sintered diamond.
 26. The chip holder according to claim 5,wherein said bearings are made of sintered diamond.
 27. The chip holderaccording to claim 6, wherein said bearings are made of sintereddiamond.
 28. A scriber apparatus comprising a mechanism for moving ascribing head in X and/or Y direction relatively to a table on which aplate made of a brittle material is put, wherein said scribing headcomprises a chip holder according to claim
 2. 29. A scriber apparatuscomprising a mechanism for moving a scribing head in X and/or Ydirection relatively to a table on which a plate made of a brittlematerial is put, wherein said scribing head comprises a chip holderaccording to claim
 3. 30. A scriber apparatus comprising a mechanism formoving a scribing head in X and/or Y direction relatively to a table onwhich a plate made of a brittle material is put, wherein said scribinghead comprises a chip holder according to claim
 4. 31. A scriberapparatus comprising a mechanism for moving a scribing head in X and/orY direction relatively to a table on which a plate made of a brittlematerial is put, wherein said scribing head comprises a chip holderaccording to claim
 5. 32. A scriber apparatus comprising a mechanism formoving a scribing head in X and/or Y direction relatively to a table onwhich a plate made of a brittle material is put, wherein said scribinghead comprises a chip holder according to claim
 6. 33. A scriberapparatus comprising a mechanism for moving a scribing head in X and/orY direction relatively to a table on which a plate made of a brittlematerial is put, wherein said scribing head comprises a chip holderaccording to claim
 7. 34. A scriber apparatus comprising a mechanism formoving a scribing head in X and/or Y direction relatively to a table onwhich a plate made of a brittle material is put, wherein said scribinghead comprises a chip holder according to claim
 8. 35. A manual cuttercomprising: a cylindrical grip; and a chip holder fixed to an end ofsaid grip, wherein said chip holder is one of the chip holders accordingto claim
 2. 36. A manual cutter comprising: a cylindrical grip; and achip holder fixed to an end of said grip, wherein said chip holder isone of the chip holders according to claim
 3. 37. A manual cuttercomprising: a cylindrical grip; and a chip holder fixed to an end ofsaid grip, wherein said chip holder is one of the chip holders accordingto claim
 4. 38. A manual cutter comprising: a cylindrical grip; and achip holder fixed to an end of said grip, wherein said chip holder isone of the chip holders according to claim
 5. 39. A manual cuttercomprising: a cylindrical grip; and a chip holder fixed to an end ofsaid grip, wherein said chip holder is one of the chip holders accordingto claim
 6. 40. A manual cutter comprising: a cylindrical grip; and achip holder fixed to an end of said grip, wherein said chip holder isone of the chip holders according to claim
 7. 41. A manual cuttercomprising: a cylindrical grip; and a chip holder fixed to an end ofsaid grip, wherein said chip holder is one of the chip holders accordingto claim 8.